The Illinois Commerce Commission says the utility needs to cut its delivery rate by $45 million.

The decision was announced Monday during an annual review and is set to take effect starting Jan. 1.

Ameren officials say they’re still reviewing the ruling. They had planned to lower the delivery rate by $37 million.

Beth Bosch, a spokeswoman for the ICC, said the rate cut was needed because Ameren “overcollected” on its previous rates.

The utility said Monday that it hasn’t had a chance to review the 2014 decision and figure out what action it may take.

Under the way the rules of formula ratemaking worked out for 2014, Ameren Illinois was always looking at a power delivery rate cut, and it had at first proposed a $30 million reduction that was later revised to $37 million.

Ameren has about 1.2 million electric customers and about 800,000 natural gas customers in central and southern Illinois.

Next up will be a natural gas delivery rate reset, and this time, an administrative law judge, who makes recommendations as part of the state’s utility bill review process, is calling for the utility to get $36 million in annual revenue from its gas customers instead of the $47 million it had asked for.